Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$197.38	3.365%	$204.0218	$204.02	$204.00	$204.00
Purchase #2	$195.80	7.732%	$210.9393	$210.94	$210.95	$210.90
Purchase #3	$145.87	6.870%	$155.8913	$155.89	$155.90	$155.90
Purchase #4	$57.90	6.180%	$61.4782	$61.48	$61.50	$61.50
Purchase #5	$185.70	5.611%	$196.1196	$196.12	$196.10	$196.10
Purchase #6	$178.73	10.507%	$197.5092	$197.51	$197.50	$197.50
Purchase #7	$231.46	13.307%	$262.2604	$262.26	$262.25	$262.30
7 purchase totals =	$1,192.84		$1,288.2198	$1,288.22	$1,288.20	$1,288.20